I would guess that you can find a qualified and licensed company or individual in your area for around $125 to $200 to do a extensive visual and internal of all panels.

I have done these before I retired and still had a contractors license for several Real Estate transactions and other individuals.

Unfortunately my state certification expired about 2 months ago.

I am in Fremont and am familiar with local wiring methods so if there is a specific question or concern feel free to describe them and I will be happy to give you any input I can.

Probably best to PM me or email: ed@robertsusa.com

Good luck,
Ed Roberts

ps: After rereading your question, you may be asking for the cost for a city permit and inspection. This I cannot help with but you can just call the inspection dept. for Hayward for the info. Do not be surprised if there is a little runaround because in over 40 years in the trade, I have never encountered a city that was more difficult to deal with for several reasons of which would not help you here. good luck.